The present invention concerns gas generators and, more particularly, concerns gas generators of the type in which a solid fuel is contacted with a liquid with which it reacts chemically to generate the desired gas. Such gas generators find employment in any situation where it is desired to have a relatively light weight, easily transportable and replaceable cartridge-type arrangement utilized as the source of a gas to avoid the obvious difficulties attendant upon such storage and use of compressed gas within a pressurized vessel.
A common type of such gas generator is one in which the solid fuel charge is a metal hydride such as, for example, a base metal hydride which reacts vigorously with water to generate hydrogen gas and leave a solid residue of a base metal hydroxide.
There are a number of difficulties associated with such devices. Among these difficulties is the fact that upon reaction with the liquid, usually water, such fuels tend to expand in volume. Since the fuels are normally contained within an enclosed container, expansion of the reacted fuel compacts the material with the result that it becomes increasingly difficult for the reacting liquid to penetrate the fuel charge and consequently the reaction often subsides while there is still left a considerable amount of unreacted solid fuel. Another difficulty with prior art generators is the difficulty in handling and storage of the fuels because of their sensitivity to moisture. Yet another difficulty is disposal of the reacted or spent fuel after the cartridge charge is exhausted.
Gas generating cartridges of this type almost universally employ water as the reactant and therefore the invention will be described with reference to water as the reactant liquid although the utilization of other liquids is within the scope of the invention.
Gas generators employing cartridges of the type with which this present invention is concerned, normally employ a reservoir of water or provide a chamber into which water is supplied and brought into contact with the solid fuel.
The prior art has provided a number of embodiments of cartridge-type gas generators. For example, U.S. Pat. No. 2,463,863, (F. Gibadlo) provides a canister contained within an outer casing. The canister has a series of relatively large perforations in it to admit water into contact with the solid fuel contained within the canister and to permit the product calcium hydroxide to be flushed out of the holes in the bottom of the canister while the hydrogen passes upwardly. The canister is a rigid member closed at both its opposite ends and containing perforations in the lower portion thereof. Another embodiment is shown in U.S. Pat. No. 2,463,862, to the same inventor, in which the bottom of the canister is provided with a recessed portion which is perforated. Both these patents recognize a difficulty involved in utilizing a fuel such as calcium hydride (preferred by the patentee) in "that the calcium hydroxide formed by the reaction tends to flocculate and collect in the can, thus covering calcium hydride not yet reacted upon and retarding the generation of additional gas." (column 2, lines 5-9 of U.S. Pat. No. 2,463,863 ).
U.S. Pat. No. 2,334,211 (C. E. Miller) shows a gas generator of the type employing a cartridge which is telescoped within an outer container and is adapted to be moved outwardly thereof for use by immersing the entire device in sea water.
U.S. Pat. No. 3,174,833 (R. H. Blackmer) discloses a hydrogen generating canister adapted to be used to supply hydrogen gas to a fuel cell.
U.S. Pat. No. 3,820,956 (Titterington et al.) discloses a gas generator containing a solid fuel which is reacted by being brought into contact with a liquid reactant. In order to maintain the liquid reactant in contact with the as yet unreacted portion of the solid fuel, a spring loaded pressure plate having a perforating knife associated therewith is utilized to push the pressure plate and the knife in a direction along the liquid delivery tube so that the knife slits the tube thereby moving the effective exit of the reactant liquid axially along the fuel charge.
It is an object of the present invention to provide a cartridge for a gas generator of the type in which a liquid reactant reacts with a solid fuel contained within the cartridge to generate a gas, which is of relatively simple construction and overcomes certain problems associated with prior art gas generator cartridges. It is another object of the present invention to provide a cartridge for a gas generator of the type described which cartridge provides an expansible solid fuel charge compartment to accommodate expansion of the reacted fuel and which provides means for more uniform distribution of the liquid reactant along the solid fuel charge.
Other objects and advantages of the present invention will be apparent from the following description thereof.